Sewing thread



Patented Dec. 5,

" UNITED STATES PATENT OFFICE Donald rimsyimfafiji Derby, England,

assignor to Celanese Corporation corporation of Delaware Application July 5, 1941, Serial No. 401,239 In Great July 26, 1940 4 Claims. (01. 57-140) This invention relates to sewing threads.

The ordinary sewing threads of commerce are made from cotton, silk, and linen, and comprise a cabled assembly of singles yarns so constructed that the singles twist and ,theIdoubling twist combins to impart coherence and smoothness with an absence ,of snarling. The cabled construction and the weight of the threads vary in accordance with the use to which they are to be put, heavier fabrics and other materials such as leatherrequiring to be seamed with more robust threads. In addition, threads intendedfor machine-sewing denier singles should have singles twist and first doubling twist whose algebraic sum does not exceed 35 turns per inch. Provided this condition is met,*the two twists niay be the same or opposite in direction; For example, the" singles twist may be -25 or 30 turns per inch, but preferably 1-5 turns per inch, and the first doubling twist inust be capable of withstanding more severe I treatment than hand-sewing threads.

In spite of the ability shown over many years of the several artificial or synthetic textile materials to replace and even improve upon natural textile materials in an enormous number of applications, the substitution of these materials in ordinary sewing. thread constructions has not met with success. I have now found, however, that a balanced cabled assembly of'threads of cellulose acetate or other cellulose ester filaments that have been suitably stretched (in the presence of softening agents for the cellulose derivatives) and then.-saponifled, so as to have high strength,

forms a highly satisfactory sewing thread. Ad- 'vantageously, the stretched filaments may be shrunk before being saponifled. The filaments of which the threads are composed may be continuous in character, or they may be used as staple fibre ofv appropriate length. Again, the filamentous threads may be continuous-filament r, properties of staple flbre yarns. I

The stretched and saponified cellulose acetate .or other cellulose ester threads may be characterised by very high strength,'e. g; of the order of 6 grams per denier or more, or 45mins per denier inthe case of the shrunk materials, and in making a cabled construction such threads. for sewing purposes the combination of singles and thread or when the thread'is run through the fingers. Heavier threads require suitably reduced twists. Examples of heavier threads are 750/780,

880, and 950 denier, which maybe approximated by using a 3-fold 2'75v denier construction. Still heavier threads of 1120,1280, 1500, 1650, 2480,

and 3720 denier correspond to threads ordinarily made of linen. Thus a 1120 denier thread may be threadsthat have been staplised or abraded so as to have something of the appearance and, other doubling twists should be suchf'as not seriously '7 to reduce the benefits resulting from this high strength. Thus, for example, a 3-fold thread using or" denier singles should have singles twist of 15-32 turns per inch in one directon and doublingtwist of 15. 30 turns per inchin the other direction; Suitable. combinations are 26/27 S,

20.5/24 z: 24 s, 22 2;; 15 s, 16.5 z; and-22 s, 15 z;

and similar combinations with reverse twists, i. e.

Z and S for the singles and doubling twists respectively.

. Again, a 6-fold (2-fold/3-fold) thread using 60 55 advantageous. For example, the thread maybe I approximated by 3-fold 340/860 denier or 6-fold /180 denier;

1080/1240 denier or 6-fold 54 20 denier.

Threads suitable for sewing boot soles can be. assembled from 750 denier singles. Thus,- a 5- fold thread may have a singles twist of 6.5 turns per inch, and doubling twist'of 5 turns per inch in the opposite direction; a 7-fold thread singles and' doubling twists of 6 and 3 respectively; and an 8-fold thread twists of 2.5 and 1.5 respectively. A staple fibre thread suitablefor the same purpose may use 438 denier singles with 4.5 turns per inch Z, two such singles being'doubled with 5 turns perinchZ, and six such doubled end finally doubled with 3 turns per inch 8. r

The singles threads may be sized to cure liveline'ss, or a hygroscopic agent maybe used (with or without. size) for the same urpose. For example, the thread may be starch soap.

given 4% ofsoluble Doubling may be yarns are passed under glass rods or brass or other i'ollers in a water trough. Care should be taken to' ensure that theseveral ends are fed at the same rate. and advantageously they are parallel wound on to a single package in an operation prior to doubling. a a

Waxing or lubricating of the final thread is ofAmerica,a

a 1650 denier thread by 3-fold g 550 denier; and a 3720 denier thread by 3-fold carried out dry, butprei'er- I ably wet doubling is' used, 1. e. the several singles treated with a low viscosity mineral oil such as spindle oil, or with olive oil, resin, ammonium stearate, or parafiin wax, with benefltto the evenness of stitch. In the case of boot sole sewing thread, waxing is carried out on the sewing or stitching machines; the stretched/shrunk/ saponified materials are capable of absorbing well the waxapplied to them in this way.

The cellulose acetate or other cellulose ester material is advantageously stretched by processes and finer deniers (e. g. 0.1) may be used if desired. When the material is used as staple fibre, the additional choice of fibre length (which may be, for example, of cotton length-about 1.5-2 inches, or linen lengthsay 5-10 inches) enables wide variation to be made in the character of the finished thread.

,Three constructions of thread according to the invention are diagrammatically shown in the accompa y g drawing.

In Fig. 1, 3 120 denier singles of cellulose acetate thread strengthened by stretching and saponification have -32 turns per inch S twist and are doubled with 15-30 turns per inch Z twist to yield a light-sewing thread.

In Fig. 2, -denier singles of strong acetate with 1-5 turns per inch S are doubled 2- "old with 5-30 turns per inch S, and 3 such folded ends are doubled with 18-30 turns per inch Z to yield a light-sewing thread.

In Fig. 3, a boot-sole sewing thread is formed from 5 750-denier singles of strong acetate with 6.5 turns per inch Z, doubled with 5 turns per inch S.

Having described my invention, what I desire to secure by Letters Patent is:

1. Sewing thread comprising a balanced cabled assembly having a denier less than 1,000 and consisting of cellulose acetate or other cellulose ester filamentous threads that have been stretched and saponified, said assembly having a lubricant stretched, shrunk and then saponified, said assembly being waxed with a solid lubricant dressing. 1 l

4. Sewing thread. comprising a. balanced cabled assembly of cellulose acetate or other cellulose ester filamentous threads that have been stretched and saponified, said assembly being waxed with a solid lubricant dressing.

"DONALD FINLAYSON. 

